Various trigger arrangements are known in the art. For example, a relatively simple trigger mechanism comprises an impact piece or hammer retentively held under the tension of a percussion spring. The impact piece is held by engagement with a stop and is released by actuation of a trigger. A safety device is used to prevent movement of one of the functioning elements of this trigger arrangement although this feature renders the mechanism somewhat more complicated.
Automatic weapons designed for selective operation in a single-firing mode further include an interrupter disposed to decouple the connection between the trigger and the impact piece, or hammer, immediately after a shot is fired. That is, they perform the interrupt function when the trigger is still active from the past shot but the weapon is already again ready to fire.
Coiling automatic weapons have also been designed for continuous firing. These weapons provide for automatic release of the impact piece as long as the trigger remains activated in continuous firing position. Such a mechanism is likewise relatively complicated.
In another example, a G3 rifle trigger arrangement comprises a hammer, a movable breechblock, a latch, a trigger, and a firing lever. The hammer has first and second stop notches and is movable between a relaxed position and a fully tensioned position. The breechblock is a movable breechblock. During its recoil, the breechblock moves the hammer from its relaxed position to the fully tensioned position. The latch is urged by a latch spring against the hammer. In this position, the latch engages the first hammer stop notch and retains it in a first tension position, which lies near the fully tensioned position. The latch also has a protrusion which engages the breechblock in such a manner that, in the ready-to-fire position, the latch is moved against the action of the latch spring and disengages the first stop.
The trigger is pivotally mounted and has an engagement lug disposed thereon. The trigger is normally urged by a trigger spring into a front rest position. Actuation of the trigger urges the spring from this rest position into a released position. The firing lever is rotatably mounted and movable in a longitudinal direction between a front and rear position. A spring arrangement normally biases the lever toward the front position as well as in a turning direction, which is counter to the swing travel of the trigger when actuated. The firing lever has an extension at an end which engages the second hammer stop notch to retain the hammer in a second tension position. This position is further remote in rotation than the first tension position. When the trigger is pulled rearward, the engagement lug disengages the lever from the second stop notch. Upon release of the lever from the second stop notch, the lever is in a position, by action of the spring arrangement, to be forwardly moved out of the action zone of the engagement lug. The lever again passes into engagement with the second stop notch. A shift-over arrangement is typically employed during continuous firing to prevent engagement of the firing lever with the second stop notch. Thus, the latch only acts on the hammer and this is freed again each time if the breechblock is closed.
In addition to being as functionally secure and durable as possible, trigger arrangements should have relatively few parts. Moreover, trigger arrangements should also be insensitive to deficient care, fouling, and harsh conditions. Trigger arrangements should also be as light as possible and their individual parts should be simple and economically manufacturable.
In the case of a rapid-fire rifle, in which the trigger arrangement is located in a pistol grip, there is the further difficulty that some functional elements cannot have multiple uses, as with automatic pistols where the closing spring can be used simultaneously as the trigger spring. Moreover, trigger arrangements for rapid firing rifles which allow selection between continuous firing and single firing and which are equipped with a safety feature are typically so complex that their construction requires undue time. Slight variations in one component create unexpected and undesired interactions.
The known trigger arrangement of the G3 rifle is functionally secure and insensitive to fouling. Also, as compared with other known trigger arrangements, it is simple in construction, as it uses only wire springs, and it is relatively economical to produce. However, the known G3 rifle trigger arrangement suffers several disadvantages. In the single firing mode, the firing lever is rotated by moving the trigger. In the process, the firing lever disengages the second stop notch so that the hammer strikes off. In the following shot, the firing lever is pressed forward by springs and its rear end is freed from the engagement lug. The lever may be rotated in the opposite direction by another spring so that its front end tends to catch the second stop notch. The hammer is tensioned during the breechblock movement and held in position by the latch until the latch is swung by the breechblock to free the first stop notch. The hammer second stop notch falls into the aforementioned extension and in so doing presses the lever to the rear against the force of a spring. If the trigger is released, it swings forward and in the process is lowered, together with the engagement lug, until the lug grips the trigger lever. This rotates the lever after being thrust rearward by the second stop post of the hammer. When the trigger is pulled again, the lever is again rotated which, in turn, releases the second stop post, so that the described would process take place again.
In order to be able to deliver continuous firing, the trigger must be pulled further in order to sufficiently swing the firing lever away from the movement zone of the second hammer stop notch. The hammer is retained by the latch only and it strikes off as soon as the breechblock is closed.
A shot should occur at the same angular position of the trigger in either single firing mode or a continuous firing mode. However, in the case of continuous firing, the trigger must be pulled back further in order to prevent the firing lever and the hammer from engaging one another. If the mobility of the index finger of the rifleman is impaired, then it is possible that, in continuous firing, the trigger is not swung far enough. In that case, instead of a burst, only a single shot is delivered.